1. Field of the Invention
The invention relates to a method and apparatus for long-term assisting the left ventricle of a heart to pump blood. A left ventricle assist device and associated methods are disclosed.
2. Description of the Related Art
With the advent of new drugs, percutaneous transluminal coronary angioplasty, commonly known as “balloon angioplasty” and the use of stents in combination with balloon angioplasty, effective treatments are available for heart disease, as it relates to coronary arteries. The major problem currently in treatment of heart disease is treating individuals having congestive heart failure or who may require a heart transplant. In this regard, it is believed that only certain very ill patients may require a heart transplant, whereas many other individuals with heart disease could benefit from a less complicated, costly, and invasive procedure, provided the individual's heart can be somehow assisted in its function to pump blood through a person's body.
To this end, left ventricle assist devices (“LVAD”) are in current use that can boost the heart's pumping ability, without replacing the patient's heart by way of a heart transplant. While presently available left ventricle assist devices do provide a benefit to patients with heart disease who require either a heart transplant or assistance in pumping blood throughout the body, it is believed that currently available devices have certain disadvantages associated with them. Conventional left ventricle assist devices generally require surgery upon the heart itself, including surgical incisions into the heart, which may weaken the heart, as well as requires a complicated procedure to implant the left ventricle assist device.
Most LVAD implantations require a midline sternotomy of the chest and utilization of cardiopulmonary bypass. Newer devices can be implanted through a lateral thoracotomy and can be done without using cardiopulmonary bypass; however, large loss of blood may occur during this procedure. It is also important to note the fact that all current long term LVAD devices require operation on the heart itself and disruption of the myocardium, which can lead to further problems, including arrhythmias, and left and right ventricular dysfunction, which can lead to poor outcomes in the patients. The major disadvantage in treating patients with chronic congestive heart failure through a surgical approach is that there is a significant risk of the surgery itself, including just the use of general anesthesia itself and the use of the heart lung machine. Patients with chronic congestive heart failure have impaired liver, renal, pulmonary and other organ function, and therefore, are prone to multiple complications following surgery. As a result, current long-term implantable left ventricular assist devices have a one-year mortality rate of greater than 30%.
Currently available left ventricle assist devices may include pumps placed within the left ventricle of the heart. Currently available devices typically include relatively long conduits, or fluid passageways, in fluid communication with the heart, and through which the person's blood must flow and be pumped therethrough. It is believed that the long conduits may become sites for thrombosis, or blood clots, which can possibly lead to strokes and other complications. During many of the procedures to implant such currently available devices, blood transfusions are required due to excessive bleeding by the patient. Additionally, the surgery upon the heart may lead to Right Heart Failure, which is the leading cause of early death in present patients receiving implanted left ventricle assist devices. Presently available left ventricle assist devices, which are connected to the aorta of the patient, can lead to unbalanced blood flow to certain branch vessels as compared to others. For example, the blood flow from the aorta to certain blood vessels that branch off the aorta, such as the coronary or carotid arteries, may be diminished. Lastly, present LVADs, which are implanted without chest surgery (percutaneous LVADs), are typically only used for a relatively short period of time, generally on the order of 7-10 days, whereas it would be desirable for a long-term treatment—on the order of months or even years—for patients with severe chronic congestive heart failure who cannot withstand conventional surgery.
Accordingly, prior to the development of the present invention, there has been no method and apparatus for long-term assisting the left ventricle of the heart to pump blood which: does not require surgery upon the heart itself; does not require long conduits, or fluid passageways, to connect the device to the heart; supplies a balanced and normal blood flow, or physiologic blood supply, to branch vessels, such as the coronary and carotid arteries; can be implanted without the use of general anesthesia; can be implanted and used for a long period of time; and can be transluminally delivered and implanted in a cardiac catheterization lab setting with minimal blood loss and relatively low risk of morbidity and mortality. Therefore, the art has sought a method and apparatus for long term assisting the left ventricles of the heart to pump blood, which: does not require surgery, or incisions upon the heart itself; does not require open chest surgery; does not require lengthy conduits, or fluid passageways, through which the blood must flow and be pumped through; is believed to provide a normal and balanced blood flow or physiologic blood supply, to branch vessels such as the coronary and carotid arteries; can be transluminally delivered and implanted without the use of general anesthesia; can be implanted and used for a long period of time; and can be implanted in a cardiac catheterization lab setting by a cardiologist with minimal blood loss and relatively low risk of morbidity and mortality.